This invention relates to power transmissions and, more particularly, to power transmissions employing a plurality of mechanical clutches and planetary gearing.
Multi-speed power transmissions, which employ mechanical clutches such as synchronizers, generally include pairs of meshing gears to establish drive or speed ratios between a transmission input shaft and a transmission output shaft. These transmissions require a pair of meshing gears for each of the forward drive ratios and one and a half pairs of gears for the reverse ratio. Each of the gear pairs includes a synchronizer or mechanical clutch, which engages one of the gears with either the main shaft or the countershaft while the other gear of that mesh is continuously driven by or with one of the other shafts.
For example, a ten speed transmission having a single reverse would require ten and a half pairs of gears, at least ten synchronizers, and a movable idler gear for the reverse ratio. The reverse ratio normally would include the input gear for first gear and an idler gear and a separate output gear. Thus, the reverse ratio is relatively close to or nearly equal to the numerical value of the first ratio.
More recently, it has been proposed to include planetary gearing in manual type transmissions. In these transmissions, multiple planetary gearsets are included. In each of the transmissions, at least one of the gearsets is a compound gearset. As is well known, compound gearsets require additional pinion sets, which increase the complexity and overall cost of a planetary gearset.
The present invention seeks to provide a multi-speed transmission having two planetary gearsets and a plurality of mechanical clutch mechanisms.
It is therefore an object of the present invention to provide an improved multi-speed power transmission.
In one aspect of the present invention, the transmission includes two planetary gearsets each of which is a simple planetary gearset.
In another aspect of the present invention, the transmission has incorporated therein two three-way synchronizers and three two-way synchronizers, which are effectively controlled to provide ten forward speed ratios and one reverse speed ratio between an input shaft and an output shaft.
In a further aspect of the present invention, one of the planetary gearsets includes a sun gear member and two identical ring gear members.
In yet a further aspect of the present invention, one of the planetary gearsets includes two identical sun gear members and one ring gear member.
In a yet still further aspect of the present invention, the dual ring gear members and dual sun gear members of each of the planetary gearsets is provided to permit input and output drives from more than one of the planetary members.